Scientists answer nature v nuture question

Australian researchers say they have the answer to the age old question of nature versus nurture when it comes to human health.

And it's basically a draw, with scientists saying it's a case of nature and nurture making equal contributions.

Experts from the University of Queensland have reviewed almost every study of twins conducted worldwide over the last 50 years.

The review, which involved 14.5 million sets of twins, found that on average the variation for human traits and diseases is 49 per cent genetic, and 51 per cent due to environmental factors.

"There has still been conjecture over how much variation is caused by genetics and how much is caused by environmental factors - what people call nature versus nurture," says Dr Beben Benyamin from UQ's Queensland Brain Institute.

"The findings show that we need to look at ourselves outside of a view of nature versus nurture, and instead look at it as nature and nurture."

While the part genetics and environmental factors play in human health is balanced for most of the traits studied, there are some exceptions.

For example, risk for bipolar disorder is about 70 per cent due to genetics and 30 per cent due to environmental factors.

The study compared the similarities of identical twins, who share all their genes, with those of non-identical twins who share only half their genes.

Professor Peter Visscher, also from the Queensland Brain Institute, said twin studies were the best basis for determining the critical drivers of human health.

"Twin studies have been the main method for researching the genetic and environmental sources of variation between humans for a long time because of the availability of the two types of twins," he says.

The study was a collaboration between UQ experts and researchers at VU University of Amsterdam, with the findings published in the journal Nature Genetics.